#define  _CRT_SECURE_NO_WARNINGS  1
#include <stdio.h>
int Fib(int n)
{
	if (n > 2)
		return Fib(n - 1) + Fib(n - 2);
	else
		return 1;

}
int main()
{
	int a = 0;
	int n = 0;
	scanf("%d", &n);

	a = Fib(n);
	printf("%d", a);

	return 0;
}